1. Field of the Invention
The present invention relates to a scroll type displacement machine, and more specifically, to a scroll type fluid machine suitably used in a refrigerating cycle of refrigerators and air conditioners.
2. Description of the Related Art
A conventional scroll type compressor uses a crank shaft directly driven by a motor to cause an orbiting scroll member to make revolution as a scroll type compressor, as disclosed, for example, in Japanese Patent Unexamined Publication No. 2-264181, and thus a radial load, which results from the pressure of a compressed gas acting on the scroll wrap portion of the orbiting scroll member, acts on the rotary sliding portion between the crank pin portion of the crank shaft and the orbiting scroll member and to the rotary sliding portion of the bearing of the motor. Further, the position in axial direction of the orbiting scroll member is regulated by such an arrangement that the orbiting scroll member is held between a fixed scroll member and a fixed plate member, and thus a thrust load, which results from a pressure difference of a gas acting on the front and back surfaces of the end plate of the orbiting scroll member, acts on the revolution sliding portion between the orbiting scroll member and the fixed scroll member or to the revolution sliding portion between the orbiting scroll member and the fixed plate member.
Further, U.S. Pat. No. 3,817,664 discloses a scroll type pump having a stationary member and a orbiting scroll supported by a spherical bearing.
The aforesaid prior art has a problem in that since a relatively large radial load is applied to a rotary sliding portion such as a crank pin portion and a bearing which has a large sliding speed, efficiency of a compressor is lowered by a large mechanical friction loss, and further strict sliding conditions are required when operating in a severe operating state, which causes wear and seizure to thereby lower reliability of the compressor. It is general in the scroll type compressor that the revolution sliding portion between the orbiting scroll member or the fixed scroll member and the revolution sliding portion between the orbiting scroll member and the fixed plate member have a relatively small sliding speed, but a thrust load larger than the radial load acts thereon, and thus a problem arises in that a mechanical friction loss due to the thrust load also lowers efficiency of the compressor in the above prior art.
The scroll type pump disclosed in U.S. Pat. No. 3,817,664 has a long distance between the stationary member and the bearing of the orbiting scroll member and this patent has the same problem as that of the aforesaid prior art.